Bharatiya Jyotihshastra (History of Indian Astronomy), translated by R. V. Vaidya v1.c5.49

v1.c5.49

In this verse the sun is said to be entering *Agni* at night. The primitive man’s attention must have been drawn to the moon just as much as to the sun or even more. Unlike the sun, the moon does not rise regularly at night. Sometimes when it rises at sunset the moon appears full in size, and then, a days pass on the moon rises later and later every day and gradually grows smaller in size. It also rapidly changes its position among the stars.